A Syrian rebel group accused the Syrian army of using chlorine gas against its fighters on Saturday in battles east of Damascus - an accusation the military swiftly denied as a fabrication.
The Failaq al-Rahman group said more than 30 people suffered suffocation as a result of the attack in Ain Tarma in the Eastern Ghouta region, which government forces have been battling to take back from insurgents.
In a statement circulated by state-run media, a military source said the army command completely denied the accusation.
"It has not used any chemical weapons in the past, and will not use them at any time".
The United States said on Wednesday the government of Syrian President Bashar al-Assad appeared so far to have heeded a warning issued earlier in the week not to carry out a chemical weapons attack after saying it saw possible preparations for one.
Western governments including the United States say the Syrian government was behind an April gas attack in the town of Khan Sheikhoun that killed dozens.
In response, the United States fired cruise missiles at the air base from which it said the attack was launched.
The Syrian government has denied any role in that attack.
On Saturday the government also dismissed a report by the international chemical weapons watchdog that said the banned nerve agent sarin was used in the April attack in Khan Sheikhoun, saying it lacked "any credibility".
A joint United Nations and OPCW investigation has found Syrian government forces were responsible for three chlorine gas attacks in 2014 and 2015 and that Islamic State militants used mustard gas.